Method for making belts



y 20, 1952 R. J. GORECKI 2,597,790

METHOD FOR MAKING BELTS Original Filed March 5, 1947 5 Sheets-Sheet 1 By%0rney y 20, 1952 R. J. GORECKI 2,597,790

METHOD FOR MAKING BELTS Original Filed Marsh 5, 1947 5 Sheets-Sheet 2 m\K \Tw 10 JSVL/ y 20, 1952 R. J. GORECKI 2,597,790

METHOD FOR MAKING BELTS Original Filed March 5, 1947 5 Sheets-Sheet 3 wi i May 20, 1952 R. J. GORECKI METHOD FOR MAKING BELTS 5 Sheets-Sheet 4Original Filed March 5. 1947 y 1952 R. J. GORECKI 2,597,790

METHOD FOR MAKING BELTS Original Filed March 5, 1947 5 Sheets-Sheet 5jzfowney Patented May 20, 1952 METHOD FOR MAKING BELTS Robert J.Gorecki, Passaic, N. J assignor to Raybestos-Manhattan, Inc., Passaic,N. J., a corporation of New Jersey Original application March 5, 1947,Serial No. 732,437. Divided and this application March 8. 1949, SerialNo. 80,299

4 Claims. 1

This invention relates to improvements in a method for manufacturingtransmission belts, and is a divisional application of my copendingapplication Serial No. 732,437, filed March 5, 1947, nowPatent No.2,518,137 entitled Method and Means for Making Belts of the V.-type,that is,

the usual trapezoidal sectioned belt, and refers specifically to amethod whereby the belt, during molding and curing, is subjected to asubstantially constant predetermined radially applied pressure whichcompensates for volume variations in the uncured belt carcass.

Heretoiore, in the manufacture of belts of the character described, ithas been the practice to insert the uncured belt carcass into either acompletely enclosed mould of substantially constant volume and cure. thesame therein under pressure and heat, or to insert the carcass into athreesided mould and establish pressure and heat in the mould, relyingupon the wrapping on the top face of the belt to confine the body of thebelt upon fourth side of the belt.

In the first case hereinbefore mentioned, the mould, being of constantvolume, depends for uniformity in belt production upon the volume of thecarcass. If the carcass contains above a predetermined volume, theexcess is squeezed out of the juncture lines of the mould and requiressubsequent trimming. This operation involve the cutting of the beltcover which seriously reduces the wear resisting characteristics of thebelt. In addition, the body of the belt, particularly the strengthmembers may be seriously distorted resulting in an improperly trackingbelt and also concentrating stresses on only a portion of the strengthmembers. If the carcass contains below a predetermined volume, the bodyof the belt does not completely fill the mould and, hence, an improperlyshaped and pressured belt results.

In the three-side type of moulding operation, excess of insufficientvolume of the carcas is refiected upon the wrapped face of the belt andfrequently results in distortion or mal-positioning of the strengthmembers resulting from non-uniform strain of the wrapped unsupportedface of the belt.

The present invention resides in a method for moulding belts of the typedescribed wherein the carcass or body of the belt is subjected tosubstantially constant pressure during cure, pressurizing of the beltbeing accomplished substantially in increments throughout the length ofthe belt at the inner radial face of the belt. This results in a beltwith its outer and lateral faces clearly moulded, its wrapping beinguncut and the strength members undistorted, or if moved,

being moved in a controlled manner.

The apparatus for carrying out my invention may take a number of forms,all being characterized by a mould having confining surfaces for theouter face and lateral sides and having a resilient pressurizing elementwhich acts radially outwardly to compress the carcass during the curingperiod.

The objects and advantages of my invention will be more apparent fromthe accompanying drawings and followin detailed description.

In the drawings:

Fig. 1 is a vertical, sectional view, parts being shown in elevation, ofa moulding machine upon which my invention may be carried out.

Fig. 2 is a fragmentary, detail perspective view, parts being shown insection, of a belt carcass.

Fig. 3 is a fragmentary detail sectional view illustrating thecomplementary mould sections.

Fig. 4 is a similar view showing a belt carcass in the mould cavityprior to the application of radial pressure.

Fig. 5 is a similar view illustrating the parts in pressurizingposition.

Fig. 6 is a fragmentary plan sectional View taken on line 6-6 of Fig. 1.

Fig. 7 is a fragmentary sectional view illustrating a modified resilientpressure member.

Fig. 8 is a similar View illustrating another modified form of resilientpressure member.

Fig. 9 is a similar view illustrating a further modification of theinvention.

Fig. 10 is a similar view illustrating a mould cavity having a dihedralouter face portion.

Fig. 11 is a similar view illustrating a mould cavity having an arcuateouter face section.

Fig. 12 is a fragmentary diagrammatic plan view of another modificationof my invention.

Fig. 13 is a sectional view taken on line [3-43 of Fig. 12.

Fig. 14 is a fragmentary enlarged sectional view of another modificationof my invention.

Referring in detail to the drawings, l indicates a moulding machinecomprising an embodiment of my invention. Machine I comprises a lowerplaten 2 which is provided with a plurality of communicating openings 3through which a heated fluidmay be passed to heat the body of theplaten. The platen 2 is supported upon legs 4 and carries a plurality ofvertically positioned standards or guides 5, which are secured togetherat their top portions by a spider or spacing member 6.

The member 5 carries a cylinder 1, having a vertically movable pistonrod or ram 8 which projects through the supporting spider 6. The ram 8is operatively connected to upper platen 9, which is also provided witha plurality of intercommunieating openings I through which a heatedfluid may be passed in order to heat the upper platen. Adjacent theedges of the platen 3,the same rides upon guides when vertical motion isimparted thereto by the piston rod 8.

An annular mould section I I is positioned upon lower platen 2 and issecured thereto by means of cap screws I2 or the like, the mouldsectionII being in heat conductive relationshipwith respect to the lower platen2 whereby the heat of the fluid passing through the intercommunicating.QP nings 3, is conducted to the section H. {line-section II comprisesthe inner portion of a mould and ha an inclined moulding surface I3,which is adapted to form one lateral wall of the belt, and a surface I4which is adapted to form the inner peripheral surface ofthe belt.

A mould section I5 is secured, by means of ca screws I6, to the lowerface of the upperplaten 3, said section being in heat conductiverelationship with respect to the upper platen 9. The section I5isannular and is adapted to comprisethe mating portion of the mouldconsisting of sections I I and I5. The section I5 is provided with aninclined surface H, which is adapted to form the opposite lateral faceof the belt and is also provided with a vertical face I8, which isadapted to form the outer face of the belt. Whenthe upper platen 9 islowered to operative 'position,-the two cooperating portions of themould comprising sections H and I5, provide a trapezoidal sectionedcavity I 3, as shown best in Fig. 3.

A supporting plate is carried by means of bolts 2| which are threadedlyengaged into the lower portion of platen 2. The supporting plate 20carries a fluid pressure cylinder 22 in which a piston (not shown)operates, said piston being operatively connected to piston rod or ram23. At the end of the piston rod 23, a, spider 24 is mounted whichcarries a plurality of radially extending arms 25.

A plurality of circularly disposed bifurcated lugs 26 are mounted uponthe supporting plate 20 by means of bolts 21 which also pass through thebase portion 28 of the cylinder 22. A bell crank lever 29 is pivotallypositioned as at 30 in each pair of lugs 26. One arm 3| of each lever 29is pivotally connected to a link 32, which at its opposite end issecured by means of nuts 33 to one of the arms 25 of spider 24. Thecentral portion of the lower platen 2 is provided with an aperture 34,into which arms 35 of the bell ,crank levers 29 extend. At the terminalends of the arm 35, rods 36 are operatively engaged by means of nuts 31.

The lower mould section I I is provided with an annular slot 38 whichopens into the mould cavity I9. Within said slot a plurality ofcircumferentially spaced segments 39 are positioned. A plurality ofapertures 40 are provided in the section I I and one of said arms 36extends through each of said apertures and is rigidly connected to thecentral portion of each of the segments 39. Endless coil spring M isalso adapted to be positioned within the radial slot 38, said coilspring embracing the outer surfaces of the segments 39. In positioningthe spring 4| upon the se ments 39, said spring is tensioned to apredetermined degree so that it snugly engages the outer faces of thesegments.

4 In the manufacture of V-belts of the type contemplated herein, theuncured belt carcass is built up of a plurality of layers of rubberizedfabric 42, or said layers may comprise rubber or a rubber composition.Positioned above the layers 542 are :a plurality of strength members 43which may comprise a plurality of longitudinally extending cords, or maycomprise wire strands, or if desired, said strength members may comprisefabric having the filler threads thereof extending longitudinally of thelength of the belt. A layer :441may be positioned above the strengthmembers 43 :and maybe constructed of a material similar-to the layers42. Frequently, it is desirable tosurroundthestrength members 43 with arelativelygsoft tieegum rubber 45.

"In tlie-construction of the usual belt, the layers 42 are frequentlyreferred to as the compression members, and the layer 44 is referred toas the tension member. The strength members 43 are the elements "whichwithstand the stress when the ibeltisiplaced :inoperation and normallysaid .strengthmembersare-disposed at or adjacent the neutral .plane ofthe :belt, that is, that portion of the belt which. when the belt isflexed around a pulley, isneither subjected to tension nor compression..Over the assembly comprising the layers 42,*strength members 43 andlayer 44, one or more fabric wrappers 46 are positioned. The wrappers.46 are frequently also rubberized.

The assembly Lhereinbefore described, is referred to as the belt carcassand is in the uncured state. in Fig. 12 the belt carcass is illustratedas being :of trapezoidal cross section. However, said belt carcass maybe of square cross section and may be formed to trapezoidal sectionduring the moulding operation. However, for purposes of illustrating myinvention, the belt carcass is shown as being :of trapezoidal sectionprior to curing and pressing.

'The carcass thus formed is endless and, when utilizing my invention,said carcass is positioned over the lower mould section II so as toposition the inner portion 41 of the belt in contact with the surface1450f the mould section II, and a side of the carcass in contact withthe inclined moulding surface 13 of said lower .section. Fluid underpressure is then introduced into the cylinder I and the uppermouldsection is brought into position, thus confining the carcass,hereinafter re- ;ferredto as carcass 48 in the cavity I9, as shown bestin Fig. 4.. It will be noted that the carcass .48 may, when the uppersection I5 is brought downwardly into position, be more or less looselydisposed within the cavity I9, depending upon the original volume of thecarcass. However, frequently the carcass 48 is positioned snugly withinthe cavity I9, but squeezed therein by means of the pressure establishedby the piston rod 8.

With the upper section I5 in the position shown in Fig. 4 fluid underpressure is introduced into the cylinder 22, thus moving the piston rod23 downwardly. This movement of the piston rod rocks the bell cranklevers 29 about their pivot points 30, and rods 36 are moved radiallyoutwardly, thus moving spring 4I into pressure contact with the innerface 4! of the carcass. This action of the machine is best illustratedin Fig. 5. It will be noted that the spring 4I establishes pressure uponthe inner face 41 of the carcass and thus moves the remaining faces ofthe carcass into contact with the faces I3, I4, I! and I8 defining themould cavity. In this manner a substantially constant pressure isbrought to bear upon the carcass. During the pressurizing operation, themould comprising the sections II and I5 is heated and simultaneouslywith the pressurizing of the carcass,the body thereof is cured.

The radialmovement of the rods 36 is relatively small as is also themovementof the rods 32. Consequently, for all practical purposes, saidrods may be considered as moving in straight lines. Consequently, theconnections with rods 32 to the spider arms 25 may be substantiallyrigid connections as may be the connections rods 36 to the bell crankarms 35.

When the belt has been properly cured, pressure is relieved from thecylinder 22 thereby permitting the bell crank lever arms 35 to moveradially inwardly under the influence of springs 4|. However, ifdesired, fluid pressure may be established on the lower portion of thepiston within cylinder 22 to positively move the bell crank lever arms35 inwardly. In view of the fact that the spring 4| is under tension,said spring will follow the inward movement of the segments 39.

The springs 4 I, in view of'the fact that diametrical pressure isestablished upon the coils thereof, are constructed of sufficientlyheavy wire as to withstand the pressure exerted by the radially outwardmovement of the arms 36 and segments 39. I have found that incompressing and curing a belt carcass of 0.26 square inch cross section,a coil spring of 30 gauge wire is suitable, when exerting a pressure of350 pounds per square inch thereupon. Of course, if the radial pressureis increased a heavier spring will be employed.

Referringparticularly to Fig. '7, I have found that a tension member 49comprising an endless rubber band of circular cross section, may beemployed instead of the spring 4|. Similar to the mounting of spring 4|within the annular notch 38, the band 49 is normally under tensionwithin said notch.

As shown best in Fig. 8, a band 59 which is constructed of rubber orother resilient material may be employed instead of the band 49, theband 59 having a dihedral face 5| which embeds itself into the innerface of the carcass during the pressing operation to establish constantpressure upon the carcass. I

Referring particularly to Fig. 10, outer mould section l5 may be soconstructed as to have an outer face IS in the form of a dihedral angle.It is not necessary that the belt carcass be constructed with a dihedralouter surface, since a belt carcass with a flat outer surface as shownin Fig. 2, may be positioned within the mould cavity and when pressureis established upon the rods 36, said pressure will tend to cause theband member 49 to establish a degree of pressure within the body of thebelt suflicient to displace the outer surface of the belt intoconformity with the dihedral outer surface [8 of the section l5.

It will be noted that although the strength members 43 may have beendisposed in a plane substantially parallel to the outer face of thebelt, the movement of the body of the carcass will tend to displace thestrength members into planes substantially parallel to the outer face l8of the outer mould section, as shown best at 52 in Fig. 10.

It will be further noted that when the plane of the strength members isnormally disposed parallel to the outer face of the belt and a flatouter surface It is used to form the outer surface of the belt,substantially no movement of the strength members takes place. However,by employing a flat outer surface carcass in a mould cavity having adihedral outer surface 18', movement of the strength members does takeplace but said movement' -is'under fcontrolled condi tions, so as'todisposeth'e plane of the strength members in'a predetermined manner. 7 v

Referring particularly to Fig. 11, an "outer mouldsection I5 is shownwhereinouter surface .l8" of the mould cavity is arcuate. In utilizingthis type of outer mould section, the belt carcass may be constructedwith a flat outer surface as illustrated in Fig. 2, and'when pressure isestablished upon the spring tensionmember 4|, the outer surfaceof-theca'rcass will move into contact withthe arcuate surface I8". Ashas been hereinbefore described in conjunction with the strength members53, which may initially have been in a plane parallel to the outersurface of the carcass, the strength members will now be disposed in theform of an are which is substantially parallel to theouter surface 18'of the mould cavity. 3 1

Referring particularly to Figs. 12' and 13 of the drawings, a modifiedmeans for operatively moving the segments into pressurizi'ng position isshown. In view of thefact that the remaininginstrmnentalities comprisingthe invention remain the same, only those portions of the inventionwhich are changed will be herein described, it being understood that theremaining parts of the machine are'similar. I I

In this form of my invention a ring 54 is mounted upon the 'upper faceof lower platen 2. Said ring is provided with a plurality ofcircumferentially spaced apertures 55, which extend radially. Connectingmembers 56 are 'slidably positioned in the apertures 55, the outer endsof said connecting members being recessed to receive the ends of rods36, which'may be secured to the connecting members 56 by means of setscrews 51. v

A disk 58 is rotatably mounted upon a shaft 59, which projects throughthe platen 2'. The lower end of shaft 59 is connected to hub 60 of acrank arm 6|, said connection comprisinga pin 62 which extendsdiametrically through hub 60 and shaft 59. The opposite end of-arm 6| ispivotally connected as at 63 to a link64,'which in turn, is pivotallyconnected as at 65 to piston rod 66. The piston rod 66 carries at itsend a piston (not shown) which'operates within a pressure cylinder 61.

The disk 58 is provided with a plurality of arcuate apertures 68, thearc of said apertures being eccentric with respect to the disk. Afollower member 69 is carried upon each of the connectors 56, saidfollower members being disposed within apertures 68.

The arrangement is such that when a belt carcass 48 is positioned withinthe mould cavity and the upper and lower platens are'heated, the twosections of the moulding are brought together as hereinbefore described.Fluid under pressure is then introduced into the upper portion of thecylinder 61 and the-piston rod'66, through the agency of the link 64,rocks the arm 6| in a clockwise direction as viewed in Fig. 12. Thismotion of the arm 6| rotates disk 53 which in turn causes the connectingmembers 56 to move radially outwardly thereby moving the segments 39into contact with the member 4| which, in turn, subjects the inner faceof the'carcass to pressure.

Referring particularly to Fig.- 14, another modification of my inventionis illustrated. In this form of my invention a platen 10 may comprisethe lower platen of a machinesimilar in construction to themachineillustrated in Fig. l

with the exception that .a different means is employed for establishingradially outward pressure upon the segments. A lower mould similar tomould H, is positionedupon the upper surface of the platen l0 and issecured thereto by means of bolts H, onl one of which is shown. Theplaten 10 is provided'with intercommunicating openings 12, through whicha heated fluid is adapted to be passed to heat said platen and also heatthe lower mould I.

The mould similar to the mould H, is of annular shape and is providedwith an annular notch or open recess 73, in which a plurality ofsegments 39 are positioned in similar fashionto the positioning ofsegments 39 in the lower mould section A band 49' similar to band 49,may be positioned in the annular recess 13 in circumscribingrelationship with respect to the segments 39'.

A distributing member '14, which may be circular in shape, is secured tothe upper face of platen 19 by means of bolts 15, only one of which isshown, said member being disposed within the lower mould section H. Apipe 16 projects through opening Tl provided in the platen l9 and isthreadedly positioned as at 18 in the member 14. The pipe 16 opens intoa cavity 19 in the central portion of the member 14, and from saidcavity a plurality of circumferentially spaced bores '80 extendradially, said bores being in communication with the cavity 19.

Each of the bores 80 opens at its opposite end into a recess 8|. Therecess 8| opens outwardly to the outer peripheral surface of the member14 and is provided with an enlarged portion 82 adjacent said outersurface, the inner defining wall of the enlarged portion being threaded.

A piston assembly 83 is adapted to be positioned in each recess 8|. Eachassembly 8| comprises a plug member 84 which carries external threadsadapted for engagement with the threads upon the inner periphery of theenlarged recess 82. A piston 85 is carried by the plug 84 and is of thetype comprising an accordion wall 86 constructed of relatively resilientmetal. This type of piston is well known and is usually referred to as asylphon piston.

The center of the plug 84 is provided with an aperture 86 in which apiston rod 81 is slidably positioned. The rod 81 terminates in a headportion 88, which is secured in fluid type relationship to the end wallof the piston 85. A coil spring 89 embraces rod 81 within the piston 85and abuts at one end against the plug 84, and at the opposite endagainst the head 88 of the piston rod, whereby a force is exerted uponthe piston 85 tending to expand the same in its normal state.

The opposite end of each piston rod 81 projects radially outwardly fromeach plug 84 and is pro vided with screw threads 99. Rods 9| are mountedupon the segments 89' and project inwardly from the mould section H inalignment with each of the piston rods 81. The outer ends of rods 9| arealso provided with screw threads 92. A sleeve or turnbuckle 93 engagesthe ends of the rods 81 and 9|, and in view of the fact that the threads90 and 92 are pitched in opposite directions, rotation of the sleeve 93tends to bring the ends of said rods closer together or remove themfurther apart, thus constituting an adjustment between the piston rods81 and the segments 39'. It is to be understood, of course, thatalthough only one piston assembly is illustrated,

the member 14 is provided with a plurality of such assemblies which arecircumferentially spaced'from each other, there being one pistonassembly for each of the segments 39', carried by the mould section II.

In operation, the mould section is employed in conjunction with an upperor outer mould section similar to the section l5, and said outer sectionis carried upon a piston actuated platen similar to the platen 9. It canreadily be seen that when the upper or outer mould section I5 ispositioned over the lower or inner mould section II', a mould cavity isprovided similar to the cavity |9. Consequently, if a belt carcass isdisposed in said mould cavity, it is positioned to receive pressurewhich may be exerted upon the band 49' by the outward movement of thevarious segments 39'.

In operation the'pipe I8 is connected at its opposite end to a source offluid under pressure (not shown). The pressure fluid may comprisecompressed air, steam or a liquid under hydraulic pressure. When fluidunder pressure is introduced into the pipe I6, said fluid is transferredto the recess 8|, thereby establishing a differential pressure upon theinner and outer surfaces of the piston 85. The piston is accordinglycompressed which causes an outward movement of the rods 81 which inturn, is transmitted to the segments 39'. In this manner pressure isestablished upon the band 49' which in turn bears upon the inner surfaceof the carcass positioned within the mould cavity. After the carcasscarried in the mould cavity is subjected to predetermined pressure andheat, the fluid pressure in pipe 16 is released and each of the pistonrods 81 is retracted radially inwardly under the influence of springs89. This action retracts the segments 39' and hence, pressure of theband 49' upon the carcass is relieved and the carcass may be readilyremoved from the mould cavity after the upper mould section has beenraised.

Referring particularly to Fig. 9, another modification of my inventionis shown. In this form of my invention 94 indicates the lower or innermould section and 95 indicates the outer or upper mould section. Whensaid sections are in operative position with respect to each other, amould cavity 96 is provided. The inner mould section 94 is provided withan annular recess 9'l which opens outwardly into the mould cavity 96.

A flexible annular tubular member 98 is positioned within the recess 91,said flexible tubular member being constructed of a material such asflexible rubber or the like. A tube 99 is positioned through a wall ofthe inner mould section 94 and-opens into the interior of the tubularmember 98 as shown best at H19 in Fig. 9.

In operation the two mould sections 94 and 95 are respectively carriedby lower and upper heated platens of a press, and consequently, saidmould sections'are heated. The belt carcass is inserted in the mouldcavity 96 and the upper or outer mould section 95 is brought intooperative moulding position with respect to the lower or inner mouldsection. Fluid under pressure is then introduced into the annulartubular member 98 through the tube 99, thereby expanding :the flexiblewalls of the tubular member 98. The expansion of the tubular member 98establishes radial pressure upon the inner surface of the carcasscarried in the cavity 98 and thus subjects'said carcass, during thecuring thereof, to a substantially uniformly distributed outward radialpressure. The fluid introduced into the tubular member 98 may compriseair under pressure or may be a hydraulic fluid.

It will be seen that herein is provided a method for moulding and curingtransmission belts especially of the V-type. My invention isparticularly characterized in that the belts are uni formly densifiedduring moulding and curing which results in a well balanced belt whichruns true and will not tend to twist during use. My invention is furthercharacterized in that no trimming of the belt is necessary aftermoulding and curing and the cover thereof remains intact. Anotheradvantage residing in my invention comprises the making of a belt whichis substantially uniformly incrementally weighted throughout its lengthwhich results in a smoothly running belt devoid of uneven inertiaeffects which are particularly noticeable and troublesome in fast movingbelts.

I am aware that many modifications of my invention may be made withoutdeparting from the spirit of the invention and, hence, I do not wish tobe limited except as necessitated by the prior art.

I claim as my invention:

1. In a method of making substantially trapezoidal cross-sectionedtransmission belts of the type comprising curable plastic material whichcomprises positioning an uncured belt carcass of solid substantiallytrapezoidal cross-section having strength members embedded thereinsubstantially parallel to and adjacent the larger of one of the twosubstantially parallel surfaces thereof in a confined zone tosubstantially completely fill said zone, applying radially outwardlyresilient pressure upon the opposite substantially parallel surface ofsaid belt remote from said strength members after said carcass has beenpositioned in said confined zone and while it is in said zone uniformlyto densify said carcass, and curing said uniformly densified carcass byheat while it is subjected to said resilient pressure.

2. In a method of making endless substantially trapezoidalcross-sectioned transmission belts of the type comprising curableplastic material which comprises confining under pressure an endlessuncured belt carcass of solid substantially trapezoidal cross sectionhaving strength members embedded therein substantially parallel to andadjacent the larger of one of the two substantially parallel outersurfaces thereof in a zone to substantially completely fill said zone,applying outwardly radially directed resilient densifying pressure uponthe opposite substantially parallel face of said belt remote from saidstrength members while said carcass is confined in said zone uniformlyto densify said carcass in said zone, and curing said uniformlydensified carcass by heat while it is subjected to said resilientdensifying pressure.

3. In a method of making endless substantially trapezoidalcross-sectioned transmission belts of the type comprising curableplastic material which comprises confining under pressure an endlessuncured belt carcass of solid substantially trapezoidal cross-sectionhaving strength members embedded therein substantially parallel to andadjacent the larger of one of the two substantially parallel outersurfaces thereof in a zone to substantially completely fill said zone,applying outwardly radially directed resilient densifying pressure uponthe opposite substantially parallel face of said belt remote from saidstrength members while said larger surface is maintained insubstantially immovable contact with a defining surface of said zone andwhile said carcass is confined in said zone uniformly to densify saidcarcass in said zone, and curing said uniformly densified carcass byheat while it is subjected to said resilient densifying pressure.

4. In a method of making transmission belts of the type comprisingcurable plastic material which comprises confining an uncured endlessbelt carcass of solid cross-section having strength members embeddedtherein substantially parallel to and adjacent an outer surface thereofin a zone to subject said carcass to initial lateral pressure while saidcarcass can move within said zone a limited degree at right angles tosaid laterally applied pressure, thereafter applying resilientdensifying pressure upon the opposite outer face of the inner surface ofsaid belt remote from said strength members while maintaining the faceof the carcass adjacent the strength members substantially stationaryand after said carcass has been initially pressed in said zone and whileit is maintained under lateral pressure in said zone to densify saidcarcass, and curing said carcass by heat while it is subjected to saidresilient densifying pressure.

ROBERT J. GORECKI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 890,409 Cox June 9, 19081,649,843 Mommy Nov. 22, 1927 1,756,266 Voth Apr. 29, 1930 1,998,817Meyer Apr. 23, 1935 2,253,792 Leavenworth Aug. 26, 1941

